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Optimizing and assigning price levels for air traffic management

TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANSPORTATION REVIEW 2002年第3-4期38卷 221-237页

作者： Deschinkel, K Farges, JL Delahaye, D Off Natl Etud & Rech Aerosp CERT F-31055 Toulouse France Univ Paris 01 CERMSEM F-75013 Paris France LOG F-31055 Toulouse France CENA F-31055 Toulouse France

Pricing policies could encourage airline companies to modify departure times and routes of their flights in order to reach a route-slot allocation target that minimizes the en-route congestion. The problem of restricting the number of price levels and the assignment of one price level to each sector at each time period is studied using a simulation based on a Logit discrete choice model. In this model, an option is defined as the combination of a departure time and a route. For each flight, a utility is associated to each option and takes into account the flying cost, the cost of ground delay and the prices of crossed sectors. The optimization of the pricing policy considers average flows and minimizes the quadratic difference between desired and expected flows on each option. A heuristic algorithm that involves successive iterations of simulated annealing and gradient methods performs this optimization. The simulated annealing assigns a price level to each sector at each time period, and the gradient algorithm computes new values of price levels. The test of the method on constructed examples indicates that the use of only four price levels does not significantly deteriorate the performance of the system with respect to the use of independent prices. (C) 2002 Elsevier Science Ltd. All rights reserved.

关键词： air traffic pricing policies simulated annealing gradient algorithm

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Grid-area coordinated load frequency control strategy using large-scale multi-agent deep reinforcement learning

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ENERGY REPORTS 2022年 8卷 255-274页

作者： Li, Jiawen Geng, Jian Yu, Tao South China Univ Technol Coll Elect Power Guangzhou 510640 Peoples R China China Elect Power Res Inst Nanjing Nanjing 210003 Peoples R China

In order to enable full participation of high-performance units controlled by different dispatching centers in the performance-based frequency regulation market, a data-driven grid-area coordinated load frequency control (GAC-LFC) strategy using unified performance-based frequency regulation market mechanism is proposed. The strategy takes into account the coordination of LFC controllers in different areas of the interconnected power grid, and accommodates a large number of highperformance units controlled by dispatching centers in secondary frequency regulation. In addition, an effective exploration-based multi-agent deep deterministic policy gradient (EE-MADDPG) algorithm is proposed as the framework algorithm. In this algorithm, the LFC controller controlled by the grid-dispatching center and the LFC controller controlled by the area-dispatching center in each area are treated as different agents. Through centralized training with decentralized execution, the coordination of LFC controllers controlled by different levels of dispatching centers in different areas can be realized. Moreover, the algorithm introduces effective exploration strategies, agents operating on various principles, and artificial intelligence functions based on imitation learning and curriculum learning, which altogether constitute a more robust strategy. Through the simulation of the four area LFC model of the China Southern Grid (CSG), it is demonstrated that the proposed method can simultaneously call more high-performance units, improve multi-area LFC control performance, and reduce the frequency regulation mileage payment in each area. (c) 2021 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： Performance-based frequency regulation market mechanism Deep reinforcement learning Grid-area coordinated load frequency control strategy Multi-agent deep deterministic policy gradient algorithm Interconnected power grid Load frequency control

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A New Stabilized Finite Element Method for Optimal Control for a Ladyzhenskaya Model for Unsteady Flows

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NUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS 2012年第1期28卷 263-287页

作者： Gao, Zhiming Kong, Fande Ma, Yichen Inst Appl Phys & Computat Math Lab Computat Phys Beijing 100088 Peoples R China Xi An Jiao Tong Univ Sch Sci Xian 710049 Shaanxi Peoples R China

This article considers the time-dependent optimal control problem of tracking the velocity for the viscous incompressible flows which is governed by a Ladyzhenskaya equations with distributed control. The existence of the optimal solution is shown and the first-order optimality condition is established. The semidiscrete-in-time approximation of the optimal control problem is also given. The spatial discretization of the optimal control problem is accomplished by using a new stabilized finite element method which does not need a stabilization parameter or calculation of high order derivatives. Finally a gradient algorithm for the fully discrete optimal control problem is effectively proposed and implemented with some numerical examples. (C) 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 28: 263-287, 2012

关键词： gradient algorithm Ladyzhenskaya model optimal control optimality condition stabilized finite element method

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Node placement optimization in ShuffleNets

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IEEE-ACM TRANSACTIONS ON NETWORKING 1998年第3期6卷 319-324页

作者： Yeung, KL Yum, TSP City Univ Hong Kong Dept Elect Engn Hong Kong Hong Kong Chinese Univ Hong Kong Dept Informat Engn Shatin Hong Kong

Node placement problem in ShuffleNets is a combinatorial optimization problem. In this paper an efficient node placement algorithm, called the gradient algorithm, is proposed. A communication cost function between a node pair is defined and the gradient algorithm places the node pairs one by one, based on the gradient of the cost function. Then two lower bounds on the traffic weighted mean internodal distance (h) over bar are proposed. The performance of the gradient algorithm is compared to the lower bounds as well as to some algorithms in the literature, Significant reduction of (h) over bar is obtained with the use of the gradient algorithm, especially for highly skewed traffic distributions. For a ShuffleNet with N = 64 nodes, the (h) over bar found is only 22% above the lower bound for the uniform random traffic distribution, and 14.7% for a highly skewed traffic distribution with skew factor gamma=100.

关键词： gradient algorithm node placement problem ShuffleNet topological design

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A new interpolation scheme for detiding vessel-mounted ADCP data in tidal reach of Yangtze Estuary

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FLOW MEASUREMENT AND INSTRUMENTATION 2016年第0期50卷 185-196页

作者： Chen, Zhigao Wang, Shengping Wang, Zhenxiang East China Univ Technol Fac Geomat Nanchang 330013 Peoples R China NASG Key Lab Watershed Ecol & Geog Environm Monitoring Nanchang 330013 Peoples R China East China Univ Technol Key Lab Digital Land & Resources Jiangxi Prov Nanchang 30013 Peoples R China Yangtze Estuary Hydrol & Water Resources Survey B Shanghai 200136 Peoples R China

Spatiotemporal fitting by the least squares method is commonly applied to separate the mean flow (runoff) and tidal current from vessel-mounted ADCP data in tidal reach. To analyze this technique in an estuary region with interaction of the runoff and tide, three sets of 29-h periods vessel-mounted ADCP data in Yangtze Estuary is tested. A diverse set of basis functions is studied and a nodes determination method, named gradient algorithm, is proposed for comparison purposes. The Green function together with a nodal configuration determined by gradient algorithm is the best option. In general, the semi major axis of the principal tidal ellipse (M2) is parallel to the riverbank and the phase of shoal waters is ahead of that of thalweg, in keeping with shallow-water tide wave dynamics. Because the tidal currents in Yangtze Estuary are explained by shallow-water tide wave dynamics, the use of the Green function and gradient algorithm in the spatiotemporal fitting by least squares technique is a promising scheme for detiding vessel-mounted ADCP data in shallow-water tide wave dynamics systems. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Vessel-mounted ADCP data Tidal reach of Yangtze Estuary gradient algorithm

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Iterative Optimization-Based ISAR Imaging With Sparse Aperture and Its Application in Interferometric ISAR Imaging

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IEEE SENSORS JOURNAL 2019年第19期19卷 8681-8693页

作者： Rong, Jiajia Wang, Yong Han, Tao Harbin Inst Technol Res Inst Elect Engn Technol Harbin 150001 Heilongjiang Peoples R China

Recently, high-resolution inverse synthetic aperture radar (ISAR) imaging with sparse aperture (SA) data has attracted increasing attention. The theory of compressive sensing (CS) suggests that an unknown sparse signal can be accurately recovered by taking advantage of very limited samples. For ISAR images, the number of the resolution cells occupied by the strong scattering points of the target is usually much smaller than that of the resolution cells of the image plane, revealing the strong sparsity trait of the ISAR signal. This trait of ISAR signal creates the conditions for incorporating CS into high-resolution ISAR imaging. In this paper, a novel iterative optimization-based SA-ISAR imaging approach is proposed. First, the SA-ISAR signal model is established and the envelope alignment is executed on the one-dimensional range profiles of the SA data. Next, the gradient-based algorithm is exploited to recover the complete signals. Then, by iteratively performing the procedures of the envelope alignment and the signal recovery, the accuracy of signal recovery can be significantly improved and a high-quality ISAR image can be obtained. Ultimately, the extension of the iterative optimization-based SA-ISAR imaging to the three-dimensional (3-D) interferometric ISAR (InISAR) imaging is successfully implemented via the traditional ISAR imagery pair interferometric method. The experiments based on the measured and simulated data are carried out to validate the superiority of the novel algorithm.

关键词： ISAR sparse aperture (SA) gradient algorithm interferometric ISAR (InISAR) envelope alignment

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Optimisation of springback in bending processes using FEM simulation and response surface method

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2005年第1-2期27卷 40-47页

作者： Lepadatu, D Hambli, R Kobi, A Barreau, A ISTIA LASQUO UPRES EA 3858 F-49000 Angers France

The aim of this work includes the springback optimisation of bending processes using the concept of experimental design and response surface methodology (RSM). The optimisation method includes two phases. The first involves the objective function prediction using design of experiments and response surface method, while the second is an optimisation process using a FORTRAN gradient algorithm. Springback of sheet parts during bending processes is simulated using finite element model (FEM) including damage evolution effects within the sheet. The numerical simulation of the damage evolution has been modelled by means of continuum damage approach. The Lemaitre damage model, taking into account the influence of triaxiality, has been implemented into ABAQUS/Standard code in order to predict the external fibres rupture evolution during the process and the material characteristics changes after bending. The simulation included die corner radius and punch-die clearance as the main variables.

关键词： bending FEM gradient algorithm optimisation response surface springback

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A CLASS OF SUPERLINEARLY CONVERGENT PROJECTION algorithmS WITH RELAXED STEPSIZES

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APPLIED MATHEMATICS AND OPTIMIZATION 1984年第1期12卷 29-43页

作者： RUSTEM, B Department of Electrical Engineering Imperial College of Science and Technology SW7 2BT London England

A quasi-Newton extension of the Goldstein-Levitin-Polyak (GLP) projected gradient algorithm for constrained optimization is considered. Essentially, this extension projects an unconstrained descent step on to the feasible region. The determination of the stepsize is divided into two stages. The first is a stepsize sequence, chosen from the range [1,2], converging to unity. This determines the size of the unconstrained step. The second is a stepsize chosen from the range [0,1] according to a stepsize strategy and determines the length of the projected step. Two such strategies are considered. The first bounds the objective function decrease by a conventional linear functional, whereas the second uses a quadratic functional as a *** introduction of the unconstrained step provides the option of taking steps that are larger than unity. It is shown that unit steplengths and subsequently superlinear convergence rates are attained if the projection of the quasi-Newton Hessian approximation approaches the projection of the Hessian at the solution. Thus, the requirement in the GLP algorithm for a positive definite Hessian at the solution is relaxed. This allows the use of strictly positive definite Hessian approximations, thereby simplifying the quadratic subproblem involved, even if the Hessian at the solution is not strictly positive definite.

关键词： Objective Function Convergence Rate Mathematical Method Feasible Region gradient algorithm

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Sensorless Control of IPMSM Based on Regression Model

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IEEE TRANSACTIONS ON POWER ELECTRONICS 2019年第9期34卷 9191-9201页

作者： Choi, Jongwon Nam, Kwanghee Bobtsov, Alexey A. Ortega, Romeo Pohang Univ Sci & Technol Dept Elect Engn Pohang 790784 South Korea ITMO Univ Dept Control Syst & Informat St Petersburg 197101 Russia CNRS SUPELEC Lab Signaux & Syst F-91192 Gif Sur Yvette France

A position-sensorless algorithm is developed for an interior permanent-magnet synchronous motor, while reflecting the saliency in an extended electromotive force term. Active flux is converted into a new linear regression form, and a high-pass filter was applied. Then, the gradient algorithm is applied to derive an estimate of the active flux in the stationary frame. The proposed observer is an inherently sensorless type because it does not require the rotor speed or position information. It is practically attractive since it does not require the use of pure integrator that is marginally stable. In addition, the observer can be constructed without the phase modulation flux linkage constant. It is basically a model-based method. However, it is easily extended to a signal injection method that is robust in the low-speed region. Ultimate boundedness is established using the persistency of excitation condition. Validity of the algorithm is demonstrated experimentally via torque and speed control with a full load in the low-speed range.

关键词： gradient algorithm interior permanent-magnet synchronous motor (IPMSM) linear regression form nonlinear observer persistency of excitation saliency sensorless control signal injection

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Modelling and identification of coupled Markov chain model with application

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INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING 1996年第6期10卷 623-634页

作者： Kennedy, RA Chung, SH AUSTRALIAN NATL UNIV FAC CHEMPROT DYNAM UNITCANBERRAACT 0200AUSTRALIA

A parametrized Markov chain model is developed to model the action of a biological ion channel. The proposed model takes the form of a set of identical binary chains which are dependent according to a coupling parameter. The outputs of these chains combine additively to give a record of ion current buried in large amounts of noise versus time. When varied, the coupling parameter realizes a range of behaviours from tight coupling to complete independence. Other model parameters describe the intrinsic characteristics of the binary chains as well as their behaviour when fully coupled. An identification procedure for the model parameters is developed based on hidden Markov modelling ideas but incorporating a gradient descent estimation algorithm. In this way we cope with the non-linear form of the dependence of the model on the parameters. The model and identification methods are tested and verified on simulated data and real biological data.

关键词： parameter estimation coupled Markov chain hidden Markov model gradient algorithm modelling membrane ion channels

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